The NHLBI Light Microscopy Core Facility (LMCF) facility has been in operation for twelve years. The LMCF consists of two people, Dr. Christian A. Combs and Dr. Daniela A. Malide, and nine microscopes located in three locations. To date we have helped researchers publish more than 170 papers and assisted almost every NHLBI-DIR Center and Branch in the past twelve years. In 2011-2012 we have help to publish twenty two papers (at the time of this report). Research conducted in the LMCF has been on many disease states, basic cell biology, and on development and implementation of new imaging techniques. The general makeup of the LMCF reflects the evolving light microscopy needs of NHLBI-DIR researchers and a commitment to provide a maximal level of assistance to the NHLBI mission. The mission of this facility is to provide state-of-the-art equipment, training, and image processing capabilities to assist NHLBI-DIR researchers in experiments involving light microscopy. Researchers that work in this facility can expect support from core personnel to whatever level suits their research. This can include advanced microscopy techniques like intra-vital two-photon microscopy and super-resolution microscopy to more ordinary wide-field imaging with a color camera Our emphasis is on training users to conduct the experiments themselves, although we are available for collaboration and all manner of assistance (experimental planning, data analysis and image processing, etc.) where required. Over the twelve years this core has been in existence we have endeavored to provide a flexible and easy to use facility that meets researchers needs and allows them to conduct their experiments in an efficient manner even if they have had no prior microscopy experience. These goals are met in several ways. First, we have an array of microscopes that offer a wide-range of microscopy techniques. These microscopes and the microscopy techniques available have been chosen and developed in response to the specific needs of researchers in the institute. In addition to the microscopes, we provide a full suite of image processing programs a dedicated 64-bit image processing workstation. Where image-processing capabilities are lacking in these programs we either write our own image processing programs. Last, we provide a comprehensive web site about all facets of the core and microscopy instruction (https://intramural.nhlbi.nih.gov/Cores/LMF/Pages/default.aspx). The goal we are working towards with the website is to allow researchers a one-stop place to learn about the core and how to plan their experiments.